Dear Sir,
I met a problem when I was trying to make a cable line to connect my
Phoenixtec UPS 500VA and computer which is running Linux 2.0.29 on a
Pentium MMX-166 on the Asus P55XT2P4 mainboard. Powerd 2.0 is used.

(DTR is connected to DSR, and via a 10K Ohm resistor to DCD, so I
supposed -11.25V is flowed to DSR.)

This is anormal comparing to the original design. DCD is not high,
because electric flows (if any) from DTR to DCD is under 0, and caused
powerd detected a power failure (DCD low).

Briefly speaking, I have some questions:
1) How come DTR is measured -11.25V but not +11.25V ?
2) Even when the relais is closed, electric flows through DTR -> resistor
-> BACKUP -> COMMON -> SG with a 19K Ohm resist. How come, under
this situation, electric should flow from DTR to SG rather than
from DTR to DCD ? Why not make the connection like the following chart: